Federal and state governments have imposed increasingly strict regulations over the years governing the levels of hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxide (NOx) pollutants that a motor vehicle may emit to the atmosphere.
In diesel engine systems, a diesel particulate filter (DPF) is provided to trap the particulate matter in the exhaust passage of the diesel engine. Conventionally, a dosing valve is mounted into the exhaust manifold of a diesel system to inject diesel fuel as the reductant into the exhaust to reduce the particulate matter and thus reduce NOx emissions. With reference to FIG. 1, a conventional reductant delivery system is shown, generally indicated at 10. The system 10 includes a control valve 12 having an inlet 14 and an outlet 16. The inlet 14 receives reductant such as diesel fuel from a tank (not shown). The fuel outlet 16 is connected to one end of the extension tube 18, with the other end of the extension tube 18 being connected to a dosing valve structure, generally indicated at 20. The dosing valve structure 20 is coupled to an exhaust boss 22 that communicates with the vehicle exhaust.
With reference to FIG. 2, the dosing valve includes a boss fitting 24 that surrounds a portion of a valve 26, inserted into the boss fitting 24. The boss fitting 24 has external threads 28 that engage internal threads in the exhaust boss 22. When the dosing valve structure 20 is coupled to the exhaust boss 22 to compress down on the valve 26, the end 30 of the boss fitting 24 comes into contact with the upper face 32 of a housing of the valve 26. As the boss fitting 24 is rotated to achieve threaded engagement with the exhaust boss 22, the valve 26 can rotate and thus disrupt the orientation of the control valve 12.
Thus, there is also a need to provide anti-rotate structure to prevent the valve 26 from rotating when the dosing valve structure 20 is coupled to the exhaust boss 22.